The present invention relates to an improved double-sided disk player for reproducing signals recorded on both sides of a disk such as a compact disk, an optical video disk, a computer disk, or the like.
Generally, the playing time for one side of a present type video disk is about 60 minutes. In order to record a movie or the like having a total playing time greater than 60 minutes, it is desirable to record continuously on both a front surface (A side) and a rear surface (B side) of the disk.
Further, in a format for high definition television being considered for future use, the playing time for one side is shortened because the information content per unit playing time must be increased.
In view of such background, it is considered that the demand for double-sided disk players will be high in the future.
Examples of double-sided disk players which have previously been proposed include a disk player provided with two pickups for the respective A and B sides, a disk player provided with a device for reversing the disk while holding it, a disk player of the pickup reverse type as disclosed in Japanese Utility Model Unexamined Publication No. 61-114558 and as shown in FIGS. 1 and 2, etc.
As shown in FIG. 1, in the disk player of the pickup reverse type, the position of the pickup is reversed from the A side to the B side after the pickup has been moved by half or more of the diameter D of the disk, as shown by a broken line in the drawing, whereafter reproduction of the B side of the disk is carried out.
In the above disk player of the pickup reverse type, a distance D/2 of 15 cm must be provided to allow for movement of the pickup (for a standard video disk size D of 30 cm), and therefore the overall length of the player must be more than 45 cm. As a result, the disk player cannot be accommodated in a standard size cabinet matching the size of, for example, standard audio equipment.
In a disk player provided with two pickups, on the other hand, the second pickup and necessary switching circuit add considerably to the total cost of the player.
Moreover, in both systems described above there is a problem in the case of a disk such as a video disk having its A side and B side manufactured separately then bonded together in that the amount of eccentricity in reproducing the B side may be larger than for the A side if a displacement is present between the centers of the two sides.
On the other hand, in the system in which the disk is reversed, a space of at least the diameter of the disk is required. Accordingly, it is impossible to reduce the size of the system to that acceptable for general consumer use.
Moreover, a pickup requires a certain height relative to the disk surface. Accordingly, in a player provided with two pickups for the respective A and B sides, or in a player of the type in which the pickup is reversed, it is required to provide a height at least twice the height from the center plane of the disk to the top of one pickup.
Further, in a player of the type in which the disk is reversed, it is required to provide at least a space of a height equal to the diameter of a disk. Accordingly, the disk player has the disadvantage that not only the disk player has a large height making it impossible to make the disk player compact, but also the disk player is complicated in structure so that its cost is high.